Chemical vapor deposition (CVD) polymerization utilizes the delivery of vapor-phase monomers to form chemically well-defined polymeric films directly on the surface of a substrate. CVD polymers are desirable as conformal surface modification layers exhibiting strong retention of organic functional groups, and, in some cases, are responsive to external stimuli. Traditional wet-chemical chain- and step-growth mechanisms guide the development of new heterogeneous CVD polymerization techniques. Commonality with inorganic CVD methods facilitates the fabrication of hybrid devices. CVD polymers bridge microfabrication technology with chemical, biological, and nanoparticle systems and assembly. Robust interfaces can be achieved through covalent grafting enabling high-resolution (60 nm) patterning, even on flexible substrates. Utilizing only low-energy input to drive selective chemistry, modest vacuum, and room-temperature substrates, CVD polymerization is compatible with thermally sensitive substrates, such as paper, textiles, and plastics. CVD methods are particularly valuable for insoluble and infusible films, including fluoropolymers, electrically conductive polymers, and controllably crosslinked networks and for the potential to reduce environmental, health, and safety impacts associated with solvents. Quantitative models aid the development of large-area and roll-to-roll CVD polymer reactors. Relevant background, fundamental principles, and selected applications are reviewed.

Simultaneous improvement of mechanical properties and lowering of the dielectric constant occur when films grown from the cyclic monomer tetravinyltetramethylcyclotetrasiloxane (V4D4) via initiated chemical vapor deposition (iCVD) are thermally cured in air. Clear signatures from silsesquioxane cage structures in the annealed films appear in the Fourier transform IR (1140 cm−1) and Raman (1117 cm−1) spectra. The iCVD method consumes an order of magnitude lower power density than the traditional plasma‐enhanced CVD, thus preserving the precursor's delicate ring structure and organic substituents in the as‐deposited films. The high degree of structural retention in the as‐deposited film allows for the beneficial formation of intrinsically porous silsesquioxane cages upon annealing in air. Complete oxidation of the silicon creates ‘Q’ groups, which impart greater hardness and modulus to the films by increasing the average connectivity number of the film matrix beyond the percolation of rigidity. The removal of labile hydrocarbon moieties allows for the oxidation of the as‐deposited film while simultaneously inducing porosity. This combination of events avoids the typical trade‐off between improved mechanical properties and higher dielectric constants. Films annealed at 410 °C have a dielectric constant of 2.15, and a hardness and modulus of 0.78 and 5.4 GPa, respectively. The solvent‐less and low‐energy nature of iCVD make it attractive from an environmental safety and health perspective.

Colloidal lithography, a popular inexpensive alternative to conventional lithography, uses two−dimensional self-assembled monolayer arrays of colloidal nanoparticles as a lithographic template. Combined with initiated chemical vapor deposition (iCVD), which offers unprecedented opportunity for producing grafted polymeric layers, this work demonstrates a generic “bottom-up” process as an inexpensive, simple, and environmentally friendly technique for creating robust well-ordered arrays of functional patterned polymeric nanostructures up to 500 nm in height. These grafted “nanobowl” patterns are produced for a broad material set of functional organic, fluorinated, and silicon containing polymers. These polymers fully retain the organic functionality of their monomeric precursors, are free of wetting defects, and are robustly tethered to the underlying substrate as shown by their ability to withstand aggressive solvent. Furthermore, using this method we pattern a novel low dielectric constant polymer down to 25 nm without the need for environmentally harmful solvents.

We present a simple one-step process to simultaneously create patterned and amine functionalized biocompatible conducting polymer nanostructures, using grafting reactions between oxidative chemical vapor deposition (oCVD) PEDOT conducting polymers and amine functionalized polystyrene (PS) colloidal templates. The functionality of the colloidal template is directly transferred to the surface of the grafted PEDOT, which is patterned as nanobowls, while preserving the advantageous electrical properties of the bulk conducting polymer. This surface functionality affords the ability to couple bioactive molecules or sensing elements for various applications, which we demonstrate by immobilizing fluorescent ligands onto the PEDOT nanopatterns. Nanoscale substructure is introduced into the patterned oCVD layer by replacing the FeCl 3 oxidizing agent with CuCl 2 .

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